In general, a seat belt system has a seat belt retractor. The seat belt retractor has a webbing spool for winding up the seat belt webbing. The webbing spool is constantly biased in the direction for winding up the webbing by a relatively small biasing force. The biasing force prevents the webbing from protracting without the application of a relatively small pulling force. Thus, tension is always applied to the webbing of the seat belt.
A rewind spring in a retractor serves to keep tension on the seat belt webbing by biasing the rotatable spool on which the webbing is wound in a webbing retracted direction. The rewind spring is traditionally in the form of a metal band, preferably a steel band, fixed at one end to an arbor at the axis of the spool and secured at its other end to a fixing point on the spring housing. The band is generally of the form used for clock springs. The band is inserted into the housing by a reverse winding process to provide the requisite tension.
A method of assembling a rewind spring into a retractor currently entails several process steps. In general a coiled metal band is mounted on an unwinding post on a purpose built jig and the end of the band is placed on the winding shaft. A winding apparatus is then lowered over the jig to reverse wind the band onto the jig. When the band is fully reverse wound then the winding apparatus is lifted and a plastic retractor mechanism cover is inserted over and fitted to the reverse wound band. The mechanism cover is then attached to a spring cover, a spring arbor is fixed to the spring and the spring if wound up to tension the spool in the webbing retracted direction. Obviously this is generally lengthy and thus expensive procedure. It is desirable to reduce the number of production steps so as to decrease time and costs.